RT, thanks for the response, I guarantee this is the same thing. I've even got the oil leak around the filler cap which seemed to go away after changing the AMM and is now back! My exhaust manifold has been redder than usual as well and I have been suspecting a lean mixture just based on that. Thanks for the tid-bit about the oil leak, I can see how that could tie in. I was scratching my head on that.

I have checked the airbox hot air valve and it is nice and tight when cold. Like you, I have changed out much of the fuel and ignition system parts and sensors and consider much of it healthy.

I agree that the system "feels" like it becomes progressively retarded as boost increases. This, of course, is leading me to wonder about the ignition ECU. Have you been able to check yours or change it out?

I've also wondered about a blockage but than I don't know if that makes sense in that full boost comes on very quick under this condition. I have not changed out the catalytic but I know mine has some of the ceramic core missing and I've often wondered if the loose bits may be clogging things up. The car seems to be putting out a good amount of exhaust at idle.

I'll post if I find anything but I'm about at the same point you are, I may have to rely on the Indy.

Thanks

Steve